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<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    <script>
        Function.prototype.mybind = function(context){
            let that = this
            let argList = Array.prototype.slice.call(arguments,1)
            return function(){
                return that.apply(context, argList)
            }
        }
        let ma={
            x:100,
            get:function (){

                return this.x
            }
        }
        
        let getx = ma.get
        getx()//undefined window.x
        ma.get()//100 ma.x
        getx.bind(ma)()//100
        getx.mybind(ma)()//100
    </script>
</body>
</html>